Circuit breaker



July 20, 1954 w H, WOODS 2,684,416

CIRCUIT BREAKER Filed oct. 25, 1952 2 sheets-sheet 1 1N VEN TOR.

m4n/Zum /f M6476 www July 20, 1954 w H WOODS 2,684,416

CIRCUIT BREAKER Filed OCL. 25, 1952 2 Sheetsheet 2 INVENTOR.

Patented July 20, 1954 CIRCUIT BREAKER William H. Woods, Garden City, Mich., assignor to Square D Company, Detroit, Mich., a corporation of Michigan Application October 23, 1952, Serial No. 316,339

Claims. 1

This invention relates to an improvement in circuit breaker construction and more particularly to an improvement in the construction of a trip-free circuit breaker.

An object of the present invention is to provide an improved circuit breaker mechanism which will trip upon the occurrence of an overload within the circuit with which it is associated regardless of whether the switching handle of the circuit breaker is held in the on position or released.

Another object of the present invention is to provide an improved circuit breaker mechanism which will have a quick-make and quick-break action when switched to the on and oil positions manually, and a quick-break action when automatically tripped regardless of whether the switching handle of the circuit breaker is held in the on position or permitted to move to the tripped position.

Further objects and features of the invention will be readily apparent to those skilled in the art from the specification and appended drawing illustrating certain preferred embodiments in which:

Figure l is a side View oi the mechanism according to the present invention showing the circuit breaker elements in the on position.

Figure 2 is a side view showing the circuit breaker elements in the off position.

Figure 3 is a side view showing the circuit breaker elements in the tripped position.

Figure 4 is a front View oi the present invention along line IV-IV of Figure 2 and with parts broken away.

Referring to the drawing, in which like reference numerals indicate like parts, the circuit breaker of the present invention is mounted within an insulating housing I. In recesses in the side walls of the insulating housing I is supported a cradle member having legs 2 and 3 and crossbars i and 5. Also mounted to the insulating housing by means of suitable mounting screws, are conductors i' and 8. Conductor 'l carries at its inner end a stationary contact 9 and conductor 3 carries at its inner end a bimetal Il.

The legs 2 and 3 oi' the cradle member are provided with opposed holes which receive a shaft I2 carrying a switching member I3 having an extending toe I4 and strengthening side plates I5 and i6. Extending through the side plates I5 and I5 and the switching member i3 is a shaft I8 upon which is pivotally mounted one end of a toggle link I9. The other end of the toggle link I9 extends through a slot in a cross member 2I which is xedly mounted to legs 22 and 23 of a substantially U-shaped contact carrying member Il also pivotally mounted on shaft I2. Surrounding the toggle link I9 and seated on the cross member 2I is a toggle spring 2Q. The member I'I carries a movable contact at 34.

Through additional holes in the legs 2 and 3 of the cradle member is mounted a shaft 25 carrying a U-shaped latching and tripping member 26 having legs 2'I and 28 pivoted on the shaft. An integral extension of the latching and tripping member 26 provides a latching tip at 29. Mounted on leg 2l of latching and tripping member 26 is a tripping pin 3I. In the leg 22 of the switching member I'I is a cutout portion 30 in which the tripping pin 3I operates. Helical tension spring 32 lmounts between the bight of the U of the latching and tripping member 2E and an extension 33 of leg 2 of the cradle member.

The cradle member is held in place in the recesses in the insulating housing I when a cover plate 31 and insulating plate 38 are secured to the base by suitable screws (not shown). An operating handle 35 is rigidly connected to the switching member I3 by means of threads on its staff 36.

The operation of the circuit breaker will now be described:

With the circuit breaker in the tripped position, as shown in Figure 3, the toe I4 of the switching member I3 is engaged by the bight of the U of the latching and tripping member 26 and movement of the operating handle 35 in a clockwise direction will lift the latching tip 29 of the tripping and latching member 26 until the free end of the bimetal iI passes thereunder and holds it in position of Figure 2 against the tension of helical spring 32.

In this normal off position of Figure 2, an upward movement of the handle will move the switching member I3 and the side plates 5 and I6 in a counterclockwise direction about shaft I2 to move the shaft I8 until it has passed to the right of the imaginary line between the pivot point of toggle link IS on the cross member 2l and the center of shaft I2. When shaft I8 has passed this line, the toggle spring 25 will force the cross member 2I to the left and cause the contact carrying member il to rotate about its pivot on shaft I2 with a snap action until the movable contact 34 makes contact with the stationary contact 9 as shown in Figure l. The overcenter action of toggle link I9, toggle spring 24 and cross member 2I will provide continuous pressure on the contacts when the circuit breaker is closed.

Upon the occurrence of a predetermined overload within the circuit with which the circuit breaker is associated, the free end of the bimetallic strip I l will flex to the left and will release the latching tip 2S. Release of the latching tip 29 will permit the latching and tripping member 2t to rotate about its pivot on shaft 25 under the tension of helical spring 32 and will cause the tripping pin 3l to move in the cutout portion 3@ I" leg 23 or the contact carrying member l1 until it strikes the right hand edge oi the cutout portion when, because the strength of helical spring 32 is greater than that of the toggle spring 24, it will rotate the contact carrying member l1 bodily about its pivot on shaft l2 to open position.

It will be apparent that regardless of whether the switching handle 35 is held in the on position or whether it is permitted to move, the release of the latching tip 29 will cause the breaker to trip due to the action of the tripping pin 3l directly on the contact carrying member l'i.

If the handle is not held on automatic trip, it will move into the trip indicating position of Figure 3 determined by the engagement toe I4 of switching member i3 with the latching and tripping member 26.

The movement of the parts to manual off position is the reverse of the movement to on position, toggle spring 25, effecting the movement with a snap action.

While certain preferred embodiments of the invention have been specifically disclosed, it is understood that the invention is not limited thereto, as many variations will be readily apparent to those skilled in the art and the invention is to be given its broadest possible interpretation within the terms of the following claims.

What is claimed is:

1. in an automatic electric circuit breaker, a stationary contact, a, movable contact cooperating with said stationary contact, an operating handle, overcenter spring means interconnecting said handle and movable Contact and operative to eiiect movement of the movable contact into and out of engagement with the stationary contact as the handle is oscillated, a spring biased trigger, current responsive means vnormally latching sait. trigger in inoperative position, and means engageable by said trigger when released by said current responsive means on current overload for effecting movement of said movable contact into disengaged position, said means and trigger operating on current overload to move said movable Contact to open position against the bias of said overcenter spring means regardless of the retention of the handle in contacts engaged position.

2. In an automaticlelectric circuit breaker, a stationary contact, a movable contact cooperating with said stationary contact, an operating handle, overcenter spring means interconnecting said handle and movable contact and operative to e'ect movement of the movable contact into and out of engagement with the stationary contact as the handle is oscillated, a spring biased trigger, current responsiveY means normally latching said trigger in inoperative position, and means engageable by said trigger when released by said current responsive means on current overload for effecting movement of said movable contact into disengaged position, said trigger moving said movable Contact against the bias of said overcenter spring` means regardless or" the retention of the handle in contacts engaged posi'- tion, means operated by said handle for moving the trigger into an operative position when the handle is moved to contacts disengaged position after an automatic trip, said last mentioned means being engaged upon trigger release to move the handle into a stable intermediate position indicating automatic opening oi the circuit breaker.

3. In an automatic electric circuit breaker, a stationary contact, a movable contact cooperating with said stationary Contact, a switching arm carrying said movable contact, an operating handle, overcenter spring means interconnecting said operating handle and switching arm, a spring biased trigger, current responsive means normally retaining said trigger in inoperative position, oscillation of said handle moving said overcenter spring means to opposite sides oi its dead center position to eifect movement of the switching arm to engaged and disengaged positions, release of said trigger by said current responsive means on current overload applying its spring bias to the switching arm independent of the handle to move the same to disengaged position against the bias of said overcenter spring means, the spring bias of the trigger being sufiicient to overcome the bias of the overcenter spring means to move the contact arm to disengaged position regardless of the maintaining of the handle in the on position.

4. in an automatic electric circuit breaker, a

stationary contact, a movable Contact cooperating with said stationary contact, a switching arm carrying said movable Contact, a pair of togglelinks, one of said links having a nxed pivot and the other having a pivotal lost motion connection with the switching arm, spring means biasing said links for breaking on opposite sides of their extended position to elect movement of the switching arm to contacts engaged and disengaged positions, anvoperating handle for rotating said one link about its fixed pivot to move the linkage through its extended position to effect movement of the switching arm manually at will, a spring biased trigger, a lost motion connection between said trigger and switching arm, current responsive means normally latching said trigger in inoperative position against its bias, said contact arm being freely movable relative to the trigger through said lost motion connection on manual operation, and means engaged by said trigger on its release by said current responsive means on overload to take-up said lost motion connection and effect direct movement of the switching arm into disengaged position against the bias oi the toggle spring and regardless of the maintenance of the handle in the on position.

5. in an automatic electric circuit breaker, a stationary contact, a movable contact cooperating vvith said stationary contact, a switching arrn carrying said movable Contact, a pair of toggle links, one of said links having a iixed pivot and the other having a pivotal lost motion connection with the switching arm, spring means biasing said links for breaking on opposite sides of their extended position to effect movement of the switching arm to contacts engaged and disengaged positions, an operating handle for rotating said one link about its xed pivot to move the linkage through its extended position to eiect movement of the switching arm manually at will, a spring biased trigger, a pin and slot connection between said trigger and switching arm whereby said switching arm is normally movable relative to the trigger through said pin and slot connection in the manual operation of the breaker, current responsive latching means for said trigger, release of the trigger by said current responsive means engaging the pin and the edge of the slot to effect direct movement of the Contact arm by the trigger biasing spring against the bias oi the toggle spring and regardless of the maintenance of the handle in the Hon position, and means for effecting reset of said trigger when the handle is moved to off position.

6. In an automatic electric circuit breaker, a stationary contact, a movable contact cooperating with said stationary contact, a manual operator, overcenter spring means interconnecting said operator and movable contact for effecting manual movement of the movable Contact into and out of its engaged position, a spring biased trigger, a lost motion connection between said trigger and movable contact whereby said movable contact is normally movable free of the trigger in its manual movement to engaged and disengaged positions, current responsive means normally latching said trigger in inoperative position against its bias and operable to release it upon the occurrence of a current overload,` and means engaged by said trigger when released by said current responsive means on overload to take up the lost motion connection and move the movable contact into disengaged position against the bias of said overcenter spring means and regardless of the maintenance of the handle in the on position.

'1. In an automatic electric circuit breaker, a stationary contact, a movable contact cooperating with said stationary contact, a manual operator, a resilient connection between said operator and movable contact biasing the movable contact into engaged position when the operator is in the on position, a spring biased trigger, current responsve means normally latching said trigger in inoperative position and operating to release the trigger upon the occurrence of a current overload, said trigger when released moving under its spring bias to move said movable contact to disengaged position against the bias of said resilient connection regardless of the maintenance of the operator in the on position, and

means for resetting said trigger when the handle is moved to off position.

8. In an automatic electric circuit breaker, a stationary contact, a movable contact cooperating with said stationary contact, a manual operator, a resilient connection between said operator and movable contact biasing the movable contact into engaged position when the operator is in the off position, a spring biased trigger, current responsive means normally latching said trigger in inoperative position and operating to release the trigger upon the occurrence of a current overload, said trigger when released moving under its spring bias to move said movable contact to disengaged position against the bias of said resilient connection regardless of the operator in the on position, and means controlled by said manual operator for returning Cil of the maintenance 65 the trigger into inoperative position when the operator is moved into off position after an automatic operation of the circuit breaker.

9. In an automatic electric circuit breaker, a stationary contact, a movable contact cooperating with said stationary contact, a manual operator, a resilient connection between said operator and movable contact biasing the movable contact into engaged position when the operator is in the on position, a spring biased trigger, current responsive means normally latching said trigger in inoperative position and operating to release the trigger upon the occurrence of a current overload, sai trigger when released moving under its spring bias to move said movable Contact to disengaged position against the bias of said resilient connection regardless of the maintenance of the operator in the on position, means controlled by said manual operator for returning the trigger into inoperative position when the operator is moved into oi'i position after an automotive operation of the circuit breaker, said last mentioned means being movable by said trigger when released and the operator is not held in on position for automatically moving the operator into a position indicating the automatic operation of the circuit breaker.

l0. In an automatic electric circuit breaker, a stationary contact, a movable contact cooperating with said stationary contact, a switching arm carrying said movable contact, a pair of toggle links, one of said links having a fixed pivot and the other having a pivotal lost motion connection with the switching arm, spring means biasing said links for breaking on the opposite sides of their extended position to efiect movement of the switching arm to contacts engaged and disengaged positions, an operating handle for rotating said one link about its xed pivot to move the linkage through its extended position to etrect movement of the switching arm manually at will, a spring biased trigger, a lost motion connection between said trigger and switching arm, current responsive means normally latching said trigger in inoperative position against its bias, said switching arm being freely movable relative to the trigger through said lost motion connection on manual operation, release of said trigger by said current responsive means on overload eiecting a take-up of said lost motion connection and direct movement of the switching arm into disengaged position against the bias of the toggle spring and regardless of the maintenance of the handle in the on position, said one link being rigid with the operating handle and having a nose thereon engageable with the trigger ior effecting return thereof to inoperative position when the handle is moved into oir position after an automatic operation of the circuit breaker.

ieferences Cited in the le of this patent UNITED STATES PATENTS Number Name Date 2,375,881 Zeller May 15, 1945 2,476,648 Zeller July 19, 1949 

